JP2017159867A - Power-assisted bicycle and pedal effort calculation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power-assisted bicycle which facilitates transmission of pedal effort as an electric signal and a pedal effort calculation method suitable for the bicycle.SOLUTION: A power-assisted bicycle 1 comprises: pedals 24 capable of applying a driving torque to a wheel drive shaft 12 through a crank shaft 21; assist drive means 32 for applying an assist torque to the wheel drive shaft 12 for assisting rotation and drive of a drive wheel 11; load detection means 40 for detecting pedal effort applied to the pedals 24; and control means 70 for controlling the assist drive means 32. The load detection means 40 comprises load detection means 41 capable of measuring a weight applied to a saddle 14, storage means 42 for storing the weight measured by the load detection means 41, and calculation means 43 for calculating the pedal effort based on a change amount of the weight in a prescribed period.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electric assist bicycle using an electric motor as auxiliary power and a pedal depression force calculation method suitable for the electric assist bicycle.

  An electrically assisted bicycle is known in which the assist amount (driving force) of an electric motor for assisting power is controlled in accordance with the pedal depression force of the bicycle so that the bicycle can run comfortably (for example, Patent Document 1). .

  FIG. 5 is a side view showing an appearance of the electrically assisted bicycle 900 described in Patent Document 1. As shown in FIG. FIG. 6 is a block diagram showing a control system of the electrically assisted bicycle 900 shown in FIG. As shown in FIGS. 5 and 6, the pedal portion 913 is provided with a torque sensor 935 and a crank frequency generator (crank FG) 936 around the pedal crank 913 </ b> A to detect and rotate the torque generated in the pedal crank 913 </ b> A. The number is detected. Further, the front wheel portion 902 is provided with a motor 951 for assist driving, a motor driver 952 for controlling the driving of the motor 951, and a motor controller 953 for controlling the motor driver 952.

  In the vehicle controller 931, the torque sensor 935 detects the pedaling force from the pedal unit 913, and sends the assisting force corresponding thereto to the motor unit 950 through the serial communication line. In addition, the bicycle mode can be changed variously by an input from the operation switch 942 of the display unit 940. Various information such as the speed of the bicycle and the remaining battery level can be displayed on the display unit 941.

  By providing these configurations, it is possible to assist according to the situation.

JP 2004-306818 A

  However, in the conventional configuration, it is necessary to attach the torque sensor 935 to the pedal portion 913 in order to detect the pedal effort. Specifically, the torque sensor 935 converts the rotational torque generated when the crankshaft connected to the pedal portion 913 is rotated into an electrical signal and transmits the electrical signal. In principle, the physical method of measuring the rotational torque of the shaft is not simple, and the torque sensor 935 becomes large and heavy. In addition, when the measurement unit of the torque sensor 935 rotates integrally with the crankshaft, a transmission mechanism (such as a wiring connection structure) of an electric signal transmitted from the measurement unit becomes difficult.

  SUMMARY OF THE INVENTION The present invention solves the above-described problems, and an object thereof is to provide a power-assisted bicycle that can easily transmit a pedal depression force as an electric signal and a pedal depression force calculation method suitable for the bicycle.

  An electric assist bicycle according to the present invention includes a wheel drive shaft that is a rotation shaft of a drive wheel, a frame that pivotally supports the wheel drive shaft so that the drive wheel can rotate, and a seat that is disposed on the frame and can be seated by a passenger. A saddle, a crankshaft pivotally supported by the frame, and an arm extending from both ends of the crankshaft are held and at least a driving torque is applied to the wheel drive shaft via the crankshaft. Possible pedal, assist drive means for assisting rotational driving of the drive wheel by applying assist torque to the wheel drive shaft, load detection means for detecting pedal depression force applied to the pedal, and the assist drive A power-assisted bicycle having control means for controlling the means, wherein the load detection means is a load detection means capable of measuring a weight applied to the saddle. Wherein to a storage means for storing the weight measured by the load detecting means, characterized in that it comprises a calculation means for calculating the pedal force based on the amount of variation of the weight in a predetermined period.

  According to this configuration, since the pedaling force applied to the pedal is calculated from the amount of change in weight measured by the load detecting means attached to a part other than the part that rotates, signal transmission can be facilitated. Therefore, it is possible to provide an electrically assisted bicycle that can easily transmit a signal for measuring the pedal effort.

  The electric assist bicycle according to the present invention further includes a rotation detection unit that detects the rotation of the crankshaft, and the control unit detects a rotation detection result of the rotation detection unit and the pedal detected by the load detection unit. It is preferable to control the torque amount of the assist torque to be applied based on the pedal effort.

  According to this configuration, by detecting the number of rotations of the pedal, it is possible to adjust the torque amount to an appropriate assist torque according to the traveling state. As a result, the possibility of excessive assist is reduced, and accidents due to excessive assist can be prevented.

  In the electrically assisted bicycle according to the present invention, a transmission means provided between the crankshaft and the drive wheel and capable of switching to a plurality of types of transmission ratios, and a transmission ratio detection capable of detecting a transmission ratio of the transmission means. And the control means includes: a speed ratio of the speed change means detected by the speed ratio detection means; a rotation detection result of the rotation detection means; and the pedal depression force detected by the load detection means. It is preferable to control the torque amount of the assist torque to be applied based on.

  According to this configuration, it is possible to adjust the torque amount of the assist torque more appropriately according to the state of the selected transmission unit and the traveling state.

  The electric assist bicycle according to the present invention further includes speed display means disposed on a handle portion connected to the frame, wherein the speed display means is a speed ratio of the speed change means detected by the speed ratio detection means. It is preferable to calculate and display the traveling speed based on the rotation detection result of the rotation detection means.

  According to this configuration, the traveling speed can be calculated using the crankshaft rotation detecting means and the gear ratio detecting means, so that the speed measuring means can also be used.

  Further, the pedal depression force calculation method of the present invention is a pedal depression force calculation method for calculating a pedal depression force applied to a pedal connected to a crankshaft, and measuring a weight applied to a seating portion at a predetermined time interval. Storing the weight in a predetermined period, calculating a variation amount of the weight, and calculating the pedal effort from the variation amount.

  According to this configuration, the pedal depression force can be calculated by measuring the change in the weight applied to the seating portion due to the reaction force generated by the depression force, so that it is not necessary to attach a torque sensor to the rotating part.

  According to the electrically assisted bicycle of the present invention, the pedaling force applied to the pedal is calculated from the amount of variation in the weight measured by the load detecting means attached to a part other than the part that rotates, thereby facilitating signal transmission. be able to. Therefore, it is possible to provide an electrically assisted bicycle that can easily transmit a signal for measuring the pedal effort.

  Further, according to the pedal depression force calculation method of the present invention, it is possible to calculate the pedal depression force by measuring the change in weight applied to the seating portion due to the reaction force generated by the depression force, so there is no need to attach a torque sensor to the rotating part.

It is a side view showing the appearance of the electrically assisted bicycle of the first embodiment. It is a block diagram which shows the structure of the electrically assisted bicycle of 1st Embodiment. It is a flowchart which shows control of the electrically assisted bicycle of 1st Embodiment. FIG. 4A is a graph showing a control example of the electrically assisted bicycle according to the first embodiment, FIG. 4A is a graph showing a time change of the measured weight together with a traveling speed, and FIG. 4B is a graph showing the calculated pedal depression force. It is the graph which showed the time change with the pedal depression force assumed when there is no assist, and FIG.4 (c) is the graph which showed the time change of the torque amount of assist torque. It is a side view which shows the external appearance of the conventional electrically assisted bicycle. It is a block diagram which shows the control system of the conventional electrically assisted bicycle.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. For easy understanding, the dimensions of the drawings are appropriately changed.

  FIG. 1 is a side view showing an appearance of the electrically assisted bicycle 1 of the first embodiment. FIG. 2 is a block diagram showing a configuration of the electrically assisted bicycle 1.

  The electrically assisted bicycle 1 of the present embodiment generates an assisting force by an electrically assisted torque so as to reduce the load on the passenger. As shown in FIG. 1, the electrically assisted bicycle 1 is held by a frame 13, a drive wheel 11 and a front wheel 17, a saddle 14 on which a rider can sit, and a rider using his / her hands. It has a handle portion 15 and a pedal 24 that is stepped on by a rider's foot.

  The pedal 24 is a set of a right pedal 24a for the rider's right foot and a left pedal 24b for the left foot, and the arms 22a and 22b extended from both ends of the crankshaft 21 attached to the drive unit 30. It is held by pedal shafts 23a and 23b provided at the tip.

  The drive unit 30 includes, for example, a gear and a chain. The pedal 24 can apply drive torque to the wheel drive shaft 12 via the crankshaft 21.

  As shown in FIG. 2, a speed change means 31 is built in the drive unit 30. The transmission means 31 is provided between the crankshaft 21 and the drive wheel 11 and has a structure that can be switched to a plurality of types of transmission ratios. The state of the transmission means 31 is detected by the transmission ratio detection means 60. The transmission ratio detection means 60 is, for example, an optical or magnetic position sensor, and is configured corresponding to the specific configuration of the transmission means 31.

  Furthermore, the electric assist bicycle 1 of the present embodiment has an assist drive means 32 and a rotation detection means 50 in the drive unit 30, unlike a normal bicycle. Furthermore, the electrically assisted bicycle 1 has a load detection means 40 for detecting the load of the passenger and a control means 70 for controlling the assist drive means 32.

  The assist drive means 32 assists the rotational drive of the drive wheel 11, and more specifically, an electric motor that operates with electric power from the battery is attached to the wheel drive shaft 12 that is the rotation shaft of the drive wheel 11. ing. The battery can be charged from commercial power or charged from regenerative power from an electric motor.

  The rotation detecting means 50 detects the rotation of the crankshaft 21. More specifically, the rotation detecting means 50 includes a magnet that rotates together with the crankshaft 21, and a magnetic rotation that detects a change in the magnetic field accompanying the rotation by a magnetic sensor. It is a sensor. The rotation detecting means 50 is not limited to a magnetic rotation sensor, and may be another method such as an optical method or a resistance method. In addition, it is preferable that the rotation detection means 50 can detect a rotation angle with high resolution, for example, what has a resolution of about 5 degrees is used.

  The load detection means 40 detects the magnitude of the pedal effort applied by the rider to the pedal 24 as the load on the rider. More specifically, the load detection unit 40 includes a load detection unit 41, a storage unit 42, and a calculation unit 43, as will be described later.

  The control means 70 is composed of a microcomputer, a power source and the like, and is fixed to the frame 13. The control means 70 uses the assist torque based on the pedal depression force calculated by the load detection means 40, the rotation of the crankshaft 21 detected by the rotation detection means 50, and the speed ratio detected by the speed ratio detection means 60. Control auxiliary power.

  Further, as shown in FIG. 1, the electrically assisted bicycle 1 of the present embodiment has a speed display means 80 attached to the handle portion 15. As described above, the electrically assisted bicycle 1 includes the rotation detecting means 50 for detecting the rotation of the crankshaft 21 and the speed ratio detecting means 60 for detecting the state of the speed changing means 31. Can be calculated. Therefore, the traveling speed of the electrically assisted bicycle 1 can be calculated, and the traveling speed can be displayed on the speed display means 80.

  The electrically assisted bicycle 1 according to the present embodiment is not one in which the load detecting means 40 is attached to the pedal 24 or the crankshaft 21, but to calculate the pedal depression force from the load change of the saddle 14 on which the rider sits. It has characteristics. When mounted on the pedal 24 or the crankshaft 21 as in a conventional torque sensor, the problem is that the structure is complicated, large, or heavy in order to detect the rotational torque generated in the rotating member. was there. Further, in the conventional configuration, when the measurement unit rotates integrally with the crankshaft 21, there is a problem that the connection structure of the electrical wiring transmitted from the measurement unit becomes difficult. In the electrically assisted bicycle 1 of the present embodiment, these problems can be solved.

  In order to solve these problems, the load detection means 40 of the electrically assisted bicycle 1 of this embodiment includes a load detection means 41, a storage means 42, and a calculation means 43, and is located at a position where the saddle 14 is fixed to the frame 13. Load detecting means 41 is provided. The load detection means 41 measures the weight generated when the passenger sits on the saddle 14. The storage means 42 stores the weight measured by the load detection means 41, and is composed of a semiconductor storage device or the like. The calculating means 43 calculates pedal depression force, and consists of a microcomputer or the like.

  Next, control of the electrically assisted bicycle 1 of the present embodiment will be described with reference to FIGS. 3 and 4. FIG. 3 is a flowchart showing the control of the electrically assisted bicycle 1. FIG. 4 is a graph showing a control example of the electrically assisted bicycle 1, FIG. 4 (a) is a graph showing the time change of the measured weight together with the traveling speed, and FIG. 4 (b) is a graph showing the calculated pedal depression force. It is the graph which showed the time change with the pedal depression force assumed when there is no assist, and FIG.4 (c) is the graph which showed the time change of the torque amount of assist torque.

  As shown in FIG. 3, the electrically assisted bicycle 1 turns on a switch in order to generate an assist force by an electrically assisted torque. No auxiliary force is generated when the switch is off. When the rider sits on the electrically assisted bicycle 1 and turns on the switch, step ST1 for measuring the weight applied to the seat S is started.

  The pedal depression force calculation method in the flowchart of FIG. 3 includes step ST1 for measuring the weight applied to the seat S at predetermined time intervals, step ST2 for storing the weight in a predetermined period, and calculating the amount of change in weight, Step ST3 for calculating the pedal depression force from the amount. In addition, although the weight concerning the seating part S is the weight added by the passenger's seating, the total weight including the weight of the saddle 14 may be sufficient.

  In step ST1, weight is periodically measured by the load detection means 41 at predetermined time intervals. In step ST2, the weight measured immediately after the start of measurement is stored as the initial weight before the rider sits down and depresses the pedal. Further, the weight measured at a predetermined time interval is stored, the amount of variation in weight from the initial weight is calculated, and the amount of variation is stored. When the weight increases from the initial weight, there is a possibility that the initial weight on which the rider is seated may not have been correctly measured. Therefore, the initial weight that is estimated to be more correct is replaced with the amount of fluctuation up to that time. Subsequently, in step ST3, the pedal effort is calculated from the stored variation in weight.

  While the power-assisted bicycle 1 is traveling, the pedal effort changes periodically. The weight measured by the load detection means 41 is reduced by the reaction force of the pedal depression force applied by the rider depressing the pedal 24. At this time, as the pedal effort changes periodically, the weight measured by the load detection means 41 decreases periodically. In the pedal depression force calculation method of the present embodiment, the magnitude of the amount of variation in which the weight is reduced from the initial weight measured by the load detection means 41 is the magnitude of the pedal depression force applied by the rider depressing the pedal 24. The pedal effort is calculated. When the rider puts the pedal 24 on the whole weight (for example, when the rider is pedaling the pedal 24 with the buttocks lifted from the saddle 14, so-called standing), the calculated pedal depression force is calculated. Is greater than the pedal effort required for travel.

  According to this configuration, the pedal depression force can be calculated by measuring the weight applied to the seat portion S, so that it is not necessary to attach a torque sensor to the rotating part of the electrically assisted bicycle 1. In addition, since the load detection means 41 is attached to a portion other than the part that rotates, the electrical wiring of the load detection means 40 is easy.

  Furthermore, a small and light load sensor can be used as the load detection means 41 for measuring the weight. As the load sensor, for example, a resistor that changes its resistance value due to strain or a piezoelectric body that generates an electromotive force due to strain can be used.

  The load detection unit 40 includes the load detection unit 41, the storage unit 42, and the calculation unit 43. However, the storage unit 42 and the calculation unit 43 may be included in the control unit 70. For example, the load detection means 41 is attached to a position where the saddle 14 is fixed and is electrically connected to the control means 70 by wiring or the like, and the control means 70 is configured to share the functions of the storage means 42 and the calculation means 43.

  In step ST4, if the rider has stepped on the pedal 24 to rotate the crankshaft 21, the rotation detecting means 50 detects the rotation of the crankshaft 21. Note that immediately after the switch is turned on, only the initial weight is measured, so step ST2 only stores the measured weight, and step ST3 and step ST4 are skipped at this time. When the pedal depression force at step ST3 is not calculated only by measuring the initial weight, the procedure returns to step ST1 and repeats the procedure for re-measurement of the weight applied to the seating portion S. Also, if the pedal effort at step ST3 is zero, or if the rotation of the crankshaft 21 is not detected at step ST4, even if the rider is seated, it is considered that he is not yet going to travel. Then, the process returns to step ST1.

  If the rotation detecting means 50 detects even a slight rotation of the crankshaft 21, it is determined in step ST5 that the stopped electric assist bicycle 1 is going to run. Then, when the rotation of the crankshaft 21 is detected in step ST4 and it is determined that the vehicle is running in step ST5, the speed ratio detecting means 60 detects the state of the speed change means 31 in step ST6. Since the transmission ratio is known by the transmission ratio detection means 60, the traveling speed is calculated in step ST7 using the rotational speed of the crankshaft 21 and the diameter of the drive wheels 11. Note that immediately after the start of traveling, the traveling speed gradually increases from zero in the stopped state, but the speed ratio of the transmission means 31 varies depending on the preference of the rider and the road surface condition. The speed display means 80 can display the traveling speed calculated in step ST7.

  As shown in FIG. 4A, the initial weight is measured before running and the pedal effort is zero. When the rider depresses the pedal 24 and rotates the crankshaft 21, the weight applied to the seating portion S is reduced by the reaction force depressing the pedal 24. From the amount of change from the initial weight at this time, the pedal effort shown in FIG. 4B is calculated. In FIG. 4B, “R” represents that the right pedal 24a is depressed, and “L” represents that the left pedal 24b is depressed. Since the right pedal 24a and the left pedal 24b are stepped on alternately, the weight fluctuation amount and the pedal depression force are periodically increased and decreased. As described above, when the pedal depression force immediately after the start of traveling increases, it is determined in step ST8 shown in FIG. 3 that the assist force by the assist torque is necessary, and the process proceeds to step ST9. On the other hand, unlike this case, when the pedal depression force is small (for example, downhill), the assist force by the assist torque is not required, so the process does not proceed to step ST9 but returns to step ST1.

  In step ST9, an appropriate amount of assist torque is calculated according to the calculated pedal depression force and travel speed. As shown in FIG. 4C, it is preferable that the pedal depression force is large and the amount of assist torque is large because acceleration is performed from zero speed immediately after the start of traveling. When a certain acceleration state is reached, the amount of torque required is small. In step ST10, the electric motor is controlled so as to generate the calculated amount of torque. The control from step ST1 is repeated at a predetermined time interval until the switch is turned off, for example, the running is stopped.

  In addition, it is preferable to repeat these controls in a short time of 1 second or less, and finer control is possible, so that a time interval is short.

  Further, if the state of the transmission means 31 is changed during traveling, the relationship between the rotational speed of the crankshaft 21 and the traveling speed changes. For example, if the gear ratio is increased during acceleration, the speed increases even if the rotation speed of the crankshaft 21 is constant. Further, if the gear ratio is increased when maintaining a constant speed, the rotational speed of the crankshaft 21 can be reduced and the pedal 24 can be operated slowly.

  If, for example, there is an uphill during traveling at a constant speed, the load increases with the same gear ratio, so that the pedal effort becomes larger than before, and the rotational speed of the crankshaft 21 also decreases. When this state is detected, the torque amount is calculated so as to increase the torque amount of the assist torque, and the assist force by the electric motor increases. Accordingly, for example, even on an uphill, it is possible to travel while maintaining a constant speed with almost no increase in pedal effort.

  In FIG. 4B, the pedal effort required to obtain the same traveling state without assist torque is indicated by a dotted line. A difference between the dotted line and the solid line (for example, T1 in FIG. 4B) corresponds to the torque amount of the assist torque. When the pedal depression force is calculated from the weight applied to the seating portion S and the pedal depression force is increased, control is performed to increase the amount of assist torque so that the vehicle can run without further increasing the pedal depression force. I understand. In addition, the torque amount of the assist torque is increased or decreased so as not to impair the feeling of pedaling force generated without assist torque, so even if assist force is generated by assist torque, you can drive like a normal bicycle. it can.

  In the electrically assisted bicycle 1 of the present embodiment, the traveling speed is calculated from the speed ratio detected by the speed ratio detecting means 60, the rotational speed detected by the rotation detecting means 50, and the diameter of the drive wheels 11. For this reason, speed measurement is possible without separately providing a means for detecting the rotation of the drive wheels 11, and the traveling speed can be displayed on the speed display means 80. Therefore, there is no need to provide a separate speed measuring means, and the cost can be reduced.

  In the electrically assisted bicycle 1 of the present embodiment, the setting is made such that the assisting force by the assist torque is generated after the rider sits on the saddle 14 and depresses the pedal 24. Further, it is preferable that no auxiliary force is generated even if the passenger does not sit down and the switch is turned on and the pedal 24 is depressed. For this reason, it is desirable to add to the conditions for starting the control that the initial weight corresponding to the weight of the passenger is measured based on the weight measured without the passenger sitting. In addition, it is preferable that the rider sets a safe travel speed range and performs control to generate an assist force by the assist torque within the speed range. It is also preferable to prepare a plurality of modes so that the level of assist can be selected according to the passenger's preference.

  Hereinafter, the effect by having set it as this embodiment is demonstrated.

  The electrically assisted bicycle 1 according to this embodiment includes a wheel drive shaft 12 that is a rotation shaft of the drive wheels 11, a frame 13 that supports the wheel drive shaft 12 so that the drive wheels 11 can rotate, and a ride that is disposed on the frame 13. Is held by a saddle 14 on which a person can sit, a crankshaft 21 pivotally supported by the frame 13, and arms 22 a and 22 b extending from both ends of the crankshaft 21 and at least via the crankshaft 21. A pedal 24 capable of applying a driving torque to the wheel drive shaft 12, assist driving means 32 for assisting the rotational drive of the drive wheels 11 by applying an assist torque to the wheel drive shaft 12, and a pedal applied to the pedal 24 A load detecting means 40 for detecting the pedaling force and a control means 70 for controlling the assist driving means 32 are provided. The load detection means 40 is based on a load detection means 41 that can measure the weight applied to the saddle 14, a storage means 42 that stores the weight measured by the load detection means 41, and a fluctuation amount of the weight in a predetermined period. Calculating means 43 for calculating the pedal depression force.

  According to this configuration, since the pedal depression force applied to the pedal 24 is calculated from the amount of variation in weight measured by the load detection means 41 attached to a portion other than the portion that rotates, the signal transmission is facilitated. Can do.

  Further, the electrically assisted bicycle 1 of the present embodiment has a rotation detection means 50 that detects the rotation of the crankshaft 21, and the control means 70 is detected by the rotation detection result of the rotation detection means 50 and the load detection means 40. It is preferable to control the amount of assist torque to be applied based on the pedal depression force.

  According to this configuration, by detecting the rotation speed of the pedal 24 (crankshaft 21), it is possible to adjust the torque amount to an appropriate assist torque according to the traveling state. As a result, the possibility of excessive assist is reduced, and accidents due to excessive assist can be prevented.

  Further, in the electrically assisted bicycle 1 of the present embodiment, a speed change means 31 provided between the crankshaft 21 and the drive wheel 11 and capable of switching to a plurality of types of speed change ratios, and a speed change ratio of the speed change means 31 can be detected. The control unit 70 is detected by the gear ratio of the transmission unit 31 detected by the transmission ratio detection unit 60, the rotation detection result of the rotation detection unit 50, and the load detection unit 40. It is preferable to control the amount of assist torque to be applied based on the pedal effort.

  According to this configuration, it is possible to adjust the torque amount of the assist torque more appropriately according to the state of the selected transmission unit 31 and the traveling state.

  Further, the electrically assisted bicycle 1 of the present embodiment includes speed display means 80 disposed on the handle portion 15 connected to the frame 13, and the speed display means 80 is the speed change detected by the gear ratio detection means 60. It is preferable to calculate and display the traveling speed based on the gear ratio of the means 31 and the rotation detection result of the rotation detecting means 50.

  According to this configuration, since the traveling speed can be calculated using the rotation detecting means 50 and the gear ratio detecting means 60 of the crankshaft 21, the speed measuring means can also be used.

  The pedal depression force calculation method of the present embodiment is a pedal depression force calculation method for calculating the pedal depression force applied to the pedal 24 connected to the crankshaft 21, and the weight applied to the seating portion S is calculated at predetermined time intervals. It has a step ST1 for measuring, a step ST2 for storing a weight in a predetermined period and calculating a variation amount of the weight, and a step ST3 for calculating a pedal depression force from the variation amount.

  According to this configuration, since it is possible to calculate the pedal depression force by measuring the change in the weight applied to the seating portion S due to the reaction force generated by the depression force, it is not necessary to attach a torque sensor to the rotating portion.

  As described above, the electrically assisted bicycle 1 according to the first embodiment of the present invention has been specifically described. However, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. It is possible to implement. For example, the present invention can be modified as follows, and these also belong to the technical scope of the present invention.

  (1) In this embodiment, although the assist drive means 32 is added to the drive part 30 which gives a drive torque to the wheel drive shaft 12 from the pedal 24 via the crankshaft 21, the assist drive means 32 is added. The wheel drive shaft may be changed to the wheel drive shaft of the front wheel 17 so that the front wheel 17 is also a drive wheel.

  (2) In the present embodiment, the pedal depression force calculation method of the electrically assisted bicycle 1 has been described. However, the pedal depression force calculation method of the present invention is applied to any system in which a rider sits on a seat and applies a depression force to the pedal. it can. For example, it can be applied to a rowing boat or a training machine.

  (3) In the present embodiment, the control means 70 controls the assisting force by the assist torque based on the calculated pedal depression force. However, separately from this, for example, an operating lever is provided on the handle portion 15 so that the rider can operate it. You may have the 2nd control means which operates a lever and adds auxiliary force. If it carries out like this, it can be set as the electrically assisted bicycle which can also drive | work without pedaling.

DESCRIPTION OF SYMBOLS 1 Electric assist bicycle 11 Drive wheel 12 Wheel drive shaft 13 Frame 14 Saddle 15 Handle part 17 Front wheel 21 Crank shaft 22a Arm 22b Arm 23a Pedal shaft 23b Pedal shaft 24 Pedal 24a Right pedal 24b Left pedal 30 Drive unit 31 Transmission means 32 Assist drive Means 40 Load detection means 41 Load detection means 42 Storage means 43 Calculation means 50 Rotation detection means 60 Gear ratio detection means 70 Control means 80 Speed display means S Seating portion

Claims (5)

A wheel drive shaft which is a rotation shaft of the drive wheel;
A frame that pivotally supports the wheel drive shaft such that the drive wheel is rotatable;
A saddle disposed on the frame and seated by a passenger;
A crankshaft pivotally supported by the frame;
A pedal that is held by arms extending from both ends of the crankshaft and can apply a driving torque to the wheel drive shaft via at least the crankshaft;
Assist driving means for assisting rotational driving of the drive wheels by applying assist torque to the wheel drive shaft;
Load detecting means for detecting pedal depression force applied to the pedal;
A power-assisted bicycle having control means for controlling the assist driving means,
The load detection means includes a load detection means capable of measuring a weight applied to the saddle, a storage means for storing a weight measured by the load detection means, and the pedal based on a variation amount of the weight in a predetermined period. An electrically assisted bicycle comprising: calculating means for calculating a pedaling force. Rotation detection means for detecting rotation of the crankshaft;
The control means controls a torque amount of the assist torque to be applied based on a rotation detection result of the rotation detection means and the pedal depression force detected by the load detection means. The electrically assisted bicycle according to 1. Transmission means provided between the crankshaft and the drive wheel, and capable of switching to a plurality of types of transmission ratios;
Gear ratio detecting means capable of detecting a gear ratio of the speed change means,
The control means is provided based on a speed ratio of the speed change means detected by the speed ratio detection means, a rotation detection result of the rotation detection means, and the pedal depression force detected by the load detection means. The electric assist bicycle according to claim 2, wherein the amount of assist torque is controlled. Having a speed display means disposed on a handle portion connected to the frame;
The speed display means calculates and displays a traveling speed based on a speed ratio of the speed change means detected by the speed ratio detection means and a rotation detection result of the rotation detection means. 3. The electric assist bicycle according to 3. A pedal depression force calculation method for calculating a pedal depression force applied to a pedal connected to a crankshaft,
Measuring the weight applied to the seating portion at predetermined time intervals;
Storing the weight in a predetermined period and calculating a variation amount of the weight;
Calculating the pedal effort from the amount of change;
A pedal depression force calculation method characterized by comprising: